SMARCA4 and neoplasm: With mutations in genes encoding SWI/SNF subunits (for example, ARID1A, ARID1B, ARID2, PBRM1, SMARCA4 and SMARCB1) collectively occurring in ∼20% of all tumours whose genomes have been characterized to date, SWI/SNF complexes are the most commonly mutated chromatin modulators in human cancer8.